Switching systems assigned to interconnect calling telephone stations with called telephone stations are often provided with automatic message accounting (AMA) equipment arranged to assess message charges against calling telephone stations. When a telephone station is utilized to originate a call to a called telephone station, the serving switching system, normally an electromechanical local office, accesses automatic message accounting equipment to record an initial entry identifying the calling telephone station, the called telephone station, and the switching system trunk equipment used to establish a call connection. After the call connection has been established, the switching system trunk equipment detects answer of the call by the called telephone station and again accesses the automatic message accounting equipment in order that an answer entry may be recorded identifying the time the call was answered. Subsequently the switching system trunk equipment detects the disconnect of the telephone stations from the call connection and again accesses the automatic message accounting equipment in order that a disconnect entry identifying the disconnect time of the call connection may be recorded. Thus, for each telephone call, the AMA equipment records three entries (i.e., initial, answer, disconnect) which in combination indicate the called and calling telephone station identities, the time that the call was answered and the time that the telephone stations were disconnected from the call connection.
The trunk equipment of a switching system is comprised of a number of trunk circuits that are arranged to connect one switching system with another to establish call connections between the calling and called telephone stations. Normally, groups of trunks bid for the services of a recorder which in turn accesses an associated perforator to record the initial, answer, and disconnect entries on paper tape.
The paper tapes produced by the various perforators are normally physically carried to a centralized data processing system where they are each read in reverse order and the three billing entries associated with each call are placed in sequence so that the requiring charges can be computed. The billing information on each tape is interspersed with entries from various of the 100 trunks which are normally served by a single recorder.
In one prior art system it was recognized that the paper tape medium was not a very good source of billing information because of its low information density, bulk, difficulty of copying, etc.; and this system provided a magnetic tape arrangement to replace the paper perforators. This arrangement gathers billing data directly from a group of recorders and places the billing data directly on magnetic tape. This system provides redundant structure limited to memory and a pair of tape decks which are switched when the end of a particular magnetic tape is reached. A malfunction in the nonduplicated hardware could possibly cause, for an indeterminate time, the loss of billing information for 10 recorders each serving up to 100 trunks. Such an outage could result in severe revenue losses. In the prior art perforator arrangement, each recorder was associated with its own perforator so most hardware problems would only invalidate the billing data for a particular recorder. However, when a data processing system is utilized to gather data from a plurality of recorders, any malfunction in key equipment in this processing unit can cause a massive loss of billing information.
It is an object of our invention to provide a data gathering system adapted to maintain the integrity of billing data reception during most data processing malfunctions.
It is a further object of our invention to provide a data gathering system in which billing information is transmitted to a centralized processing unit, and even during partial system outages, billing data is transmitted to the centralized processing unit in a manner such that it can maintain the continuity of received billing information.
It is a further object of our invention to maintain the continuity of billing data reception even when recorders are manually associated or disassociated with data processing units.